Water-based emulsion containing isoxafenacil and preparation method therefor

Abstract

The present application relates to the technical field of water-based emulsions, and specifically relates to a water-based emulsion containing isoxafenacil, and a preparation method therefor. By mass percentage, raw materials for the preparation thereof comprise: 5%-30% isoxafenacil, 10%-40% solvent, 3%-5% emulsifier, 3%-5% antifreeze, 0.01%-0.1% defoamer, and 0.1%-1% stabilizer, the balance being water. The water-based emulsion containing isoxafenacil provided by the present application has good high-temperature storage stability, with an isoxafenacil decomposition rate of less than 5%, satisfying a 2-year shelf life; it also has good dispersibility and dilutability in water of different hardnesses; the emulsion can be simply mixed with other formulation products before aerial spraying, showing good tank-mix compatibility, and is not prone to flocculation, layering, or other abnormalities.

Description

A pyrimethanil-containing water-in-oil emulsion and its preparation method

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on October 9, 2024, application number 202411398494.3, entitled "A water-in-oil emulsion containing pyrimethanil and its preparation method", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of water-in-oil emulsion technology, specifically to a water-in-oil emulsion containing pyrimethanil and its preparation method. Background Technology

[0004] The state has set higher requirements for green and environmentally friendly agricultural production. The development of water-based green and environmentally friendly pesticide formulations is one of the environmental protection technologies advocated and strongly supported by the state. With the development of aerial spraying technology for pesticides, herbicides also need to have outstanding tank mixing effects and not have incompatibility issues. Furthermore, herbicides need to have characteristics such as low toxicity, high efficiency, rapid effect, low residue, and wide application range, especially when mixed with other herbicides, the synergistic effect is obvious. Pyrimethanil has the characteristics of low toxicity, high efficiency, rapid effect, low residue, and wide application range. However, pyrimethanil is insoluble in water, and the molecular structure of pyrimethanil contains ester bonds, which are prone to breakage in aqueous systems, causing pyrimethanil to decompose. This also makes it difficult to ensure the stability of the water-in-oil emulsion.

[0005] Chinese patent application number CN202210457620.2 discloses a dispersible oil suspension containing pyrimethanil and its preparation method. This patent solves the decomposition problem of pyrimethanil in dispersible oil suspensions, but does not provide a solution to the problem of the stability of pyrimethanil in aqueous systems.

[0006] Therefore, providing a water-in-oil emulsion with good stability and the ability to reduce the decomposition rate of pyrimethanil is the main technical problem that needs to be solved. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the first aspect of this application provides a water-in-oil emulsion containing pyrimethanil, wherein the raw materials for its preparation include 5% to 30% pyrimethanil, 10% to 40% solvent, 3% to 5% emulsifier, 3% to 5% antifreeze, 0.01% to 0.1% defoamer, 0.1% to 1% stabilizer, and water as the balance.

[0008] In one embodiment, the raw materials for its preparation include 10% to 20% pyrimethanil by mass percentage.

[0009] In one embodiment, the solvent includes a co-solvent and a main solvent, and the raw materials for preparation contain 10% to 15% co-solvent and 20% to 30% main solvent.

[0010] In one embodiment, the co-solvent is selected from one or a combination of two of decanoic acid and octadecanamide.

[0011] In one embodiment, the main solvent comprises solvent oil.

[0012] In one embodiment, the solvent oil is 150# solvent oil.

[0013] In one embodiment, the emulsifier includes one or a combination of two of EOPO block polyether and castor oil polyoxyethylene ether.

[0014] In one embodiment, the EOPO block polyether is of a type including, but not limited to, one or more combinations of 5000HM, ETHYLAN NS-500LQ, and 1125.

[0015] In one embodiment, the castor oil polyoxyethylene ether is, but is not limited to, one or more combinations of EMULPON CO-360 and 3600B.

[0016] In one embodiment, the emulsifier comprises a combination of castor oil polyoxyethylene ether of type 3600B and EOPO block polyether of type 1125.

[0017] In one embodiment, the emulsifier comprises a combination of castor oil polyoxyethylene ether of type EMULPON CO-360 and EOPO block polyether of type ETHYLAN NS-500LQ.

[0018] In one embodiment, the emulsifier comprises a combination of castor oil polyoxyethylene ether of type EMULPON CO-360 and EOPO block polyether of type 5000HM.

[0019] In one embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is (1-3):(1-3).

[0020] In one optional embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is 1.75:2.25.

[0021] In one optional embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is 1:3.

[0022] In one optional embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is 1.25:2.75.

[0023] In one optional embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is 1:1.

[0024] In one optional embodiment, the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is 2.5:1.5.

[0025] In order to improve the storage stability of pyrimethanil-containing water emulsions, the inventors discovered during the experiment that when castor oil polyoxyethylene ether and EOPO block polyether are used in combination, especially when the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is (1-3):(1-3), the stability of pyrimethanil-containing water emulsions can be improved, ensuring that the pyrimethanil-containing water emulsions still have good stability after low-temperature and high-temperature storage.

[0026] In one embodiment, the stabilizer comprises one or more of the following: disodium hydrogen phosphate, triethanolamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tris(2,4-di-tert-butylphenyl) phosphite.

[0027] To improve the stability of pyrimethanil-containing water-in-oil emulsions, ensuring a 2-year shelf-life stability, and addressing the issue of pyrimethanil decomposition exceeding 5% due to ester bond breakage during the development of water-in-oil emulsions, the inventors discovered during experiments that adding stabilizers can improve the stability of pyrimethanil-containing water-in-oil emulsions. However, they found that not all stabilizers can improve the stability of pyrimethanil-containing water-in-oil emulsions and control the decomposition rate to less than 5%. A more effective approach involves using specific castor oil polyoxyethylene ether and EOPO block polyether, combined with the stabilizer hydrogen phosphate. The pyrimethanil-containing water-in-oil emulsion obtained by combining one or more of the following: disodium, triethanolamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tris(2,4-di-tert-butylphenyl) phosphite, exhibits good stability and can control the ester bond cleavage of pyrimethanil in water, thus preventing a high decomposition rate. This may be because the addition of specific stabilizers and emulsifiers, along with controlling the pH range of the pyrimethanil-containing water-in-oil emulsion, can reduce the decomposition rate of pyrimethanil to within 5%, thereby improving the application effect of the pyrimethanil-containing water-in-oil emulsion and obtaining a qualified water-in-oil product.

[0028] In one embodiment, the stabilizer is disodium hydrogen phosphate, and the pH of the pyrimethanil-containing emulsion is 7.20-7.80.

[0029] In a preferred embodiment, the stabilizer is disodium hydrogen phosphate, and the pH of the pyrimethanil-containing emulsion is 7.51-7.70.

[0030] To ensure good storage stability of pyrimethanil-containing aqueous emulsions and reduce the decomposition rate of pyrimethanil during storage and at high temperatures, keeping the decomposition rate below 5%, the inventors unexpectedly discovered during experiments that the pH value of the pyrimethanil-containing aqueous emulsion changes after the addition of a stabilizer. When the stabilizer is disodium hydrogen phosphate, combined with castor oil polyoxyethylene ether and EOPO block polyether, controlling the pH of the pyrimethanil-containing aqueous emulsion at 7.20-7.80 prevents post-shear phase inversion, thus reducing the decomposition rate of pyrimethanil during storage and at high temperatures. Furthermore, when the pH of the pyrimethanil-containing aqueous emulsion is 7.51-7.70, demulsification and phase inversion do not occur after storage at high temperatures, and the decomposition rate of pyrimethanil in the pyrimethanil-containing aqueous emulsion is controlled below 5%, resulting in a qualified product.

[0031] In one embodiment, the stabilizer is triethanolamine, and the pH of the pyrimethanil-containing emulsion is 8.0-10.0.

[0032] In a preferred embodiment, the stabilizer is triethanolamine, and the pH of the pyrimethanil-containing emulsion is 8.49-9.75.

[0033] During the experiment, the inventors unexpectedly discovered that when triethanolamine was used as a stabilizer in combination with castor oil polyoxyethylene ether and EOPO block polyether, controlling the pH of the pyrimethanil-containing water emulsion to 8.0-10.0 would not cause post-shear phase inversion in the pyrimethanil-containing water emulsion. Furthermore, it could reduce the decomposition rate of pyrimethanil in the pyrimethanil-containing water emulsion during storage and at high temperatures, keeping the decomposition rate of pyrimethanil in the pyrimethanil-containing water emulsion below 5%, thus obtaining a qualified product. Moreover, it prevented demulsification and phase inversion of the pyrimethanil-containing water emulsion after storage at high temperatures, also resulting in a qualified product.

[0034] The stabilizer is one or a combination of two of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite, and the pH of the pyrimethanil-containing emulsion is 5.0-6.0.

[0035] In one embodiment, the stabilizer is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the pH of the pyrimethanil-containing aqueous emulsion is 5.0-6.0.

[0036] In one embodiment, the stabilizer is tris(2,4-di-tert-butylphenyl) phosphite, and the pH of the pyrimethanil-containing aqueous emulsion is 5.0-6.0.

[0037] During the experiment, the inventors discovered that when pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris(2,4-di-tert-butylphenyl) phosphite was used as a stabilizer, and combined with castor oil polyoxyethylene ether and EOPO block polyether respectively, the pH of the pyrimethanil-containing aqueous emulsion was controlled at 5.0-6.0, which prevented the pyrimethanil-containing aqueous emulsion from undergoing post-shear phase inversion. Furthermore, it reduced the pyrimethanil decomposition rate during storage and at high temperatures, keeping the pyrimethanil decomposition rate in the aqueous emulsion below 5%, thus obtaining a qualified product. Additionally, it prevented demulsification and phase inversion after storage at high temperatures.

[0038] The second aspect of this application provides a method for preparing a pyrimethanil-containing water-in-oil emulsion, comprising the following steps:

[0039] S1. Add the solvent to the oil phase preparation vessel, and then add pyrimethanil and emulsifier to the oil phase preparation vessel in sequence and stir to obtain the oil phase;

[0040] S2. Aqueous phase is obtained by mixing water, antifreeze, and defoamer;

[0041] S3. The oil phase is added to the aqueous phase and sheared to obtain a mixture, and a stabilizer is added to the mixture to obtain a pyrimethanil-containing emulsion.

[0042] In one embodiment, the particle size D of the pyrimethanil-containing water emulsion is obtained in step S3. 97 It is 2-3 μm.

[0043] In one embodiment, in step S1, a solvent is added to an oil phase preparation vessel, then pyrimethanil is added to the oil phase preparation vessel, and the mixture of solvent and pyrimethanil is heated to 50°C to dissolve and clarify. Then, an emulsifier is added to the mixture and stirred until homogeneous to obtain an oil phase. Beneficial effects

[0044] 1. In this application, disodium hydrogen phosphate is used as a stabilizer. When the pH of the pyrimethanil-containing water emulsion is controlled at 7.20-7.80, the pyrimethanil-containing water emulsion will not experience post-shear phase inversion. This can reduce the decomposition rate of pyrimethanil during storage and at high temperatures. Furthermore, when the pH of the pyrimethanil-containing water emulsion is 7.51-7.70, the pyrimethanil-containing water emulsion will not experience unstable problems such as water separation, demulsification, or phase inversion after storage at high temperatures, thus obtaining a qualified product.

[0045] 2. In this application, triethanolamine is used as a stabilizer to work in combination with castor oil polyoxyethylene ether and EOPO block polyether. When the pH of the pyrimethanil-containing water emulsion is controlled at 8.0-10.0, problems such as water separation, demulsification, and phase inversion will not occur during storage. Furthermore, the decomposition rate of pyrimethanil in the pyrimethanil-containing water emulsion during storage and under high-temperature storage conditions can be reduced to less than 5%, thus obtaining a qualified product.

[0046] 3. In this application, when pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris(2,4-di-tert-butylphenyl) phosphite is used as a stabilizer, it is combined with castor oil polyoxyethylene ether and EOPO block polyether, respectively. When the pH of the pyrimethanil-containing water emulsion is controlled at 5.0-6.0, the problem of post-shear phase inversion of the pyrimethanil-containing water emulsion is avoided. This can reduce the pyrimethanil decomposition rate of the pyrimethanil-containing water emulsion to less than 5% during storage and at high temperatures, thus obtaining a qualified product.

[0047] 4. In this application, castor oil polyoxyethylene ether and EOPO block polyether are used in combination. When the mass ratio of castor oil polyoxyethylene ether to EOPO block polyether is (1-3):(1-3), the resulting pyrimethanil-containing water emulsion will not experience water separation, stratification, demulsification, or phase inversion during storage. This can improve the storage stability of the pyrimethanil-containing water emulsion and ensure that it has a 2-year shelf-life stability.

[0048] 5. The pyrimethanil-containing emulsion provided in this application shows no flocculation, no stratification, and no sedimentation when diluted with water of different hardness and temperature, all of which are in a qualified state. The pyrimethanil-containing emulsion has strong versatility and can be used for dilution and application in water from different regions.

[0049] 6. The pyrimethanil-containing emulsifiable concentrate provided in this application has the characteristic of rapid weed control.

[0050] 7. The pyrimethanil-containing emulsion provided in this application has good high-temperature storage stability, ensuring that the pyrimethanil-containing emulsion has a shelf life stability of 2 years, and solves the problem that the ester bond breaking of pyrimethanil caused by the development of pyrimethanil into an emulsion results in a pyrimethanil decomposition rate of more than 5%. Attached Figure Description

[0051] Figure 1 shows the state of the pyrimethanil-containing emulsion provided in the example during storage without any abnormalities.

[0052] Figure 2 shows the water separation and stratification state of the three water-in-oil emulsion samples containing pyrimethanil provided in Example 3.

[0053] Figure 3 shows the state of demulsification and phase inversion of the pyrimethanil-containing emulsion provided in Example 4.

[0054] Figure 4 shows the control effect of the pyrimethanil-containing emulsion on reeds after application in Example 7.

[0055] Figure 5 shows the control effect of the pyrimethanil-containing emulsion provided in Example 7 on goosegrass before and 3-7 days after application.

[0056] Figure 6 shows the control effect of the pyrimethanil-containing emulsion on goosegrass 14-21 days after application in Example 7.

[0057] Figure 7 shows the control effect of the pyrimethanil-containing emulsion provided in Example 7 on Erigeron brevis before and 3-7 days after application.

[0058] Figure 8 shows the control effect of the pyrimethanil-containing emulsifiable concentrate provided in Example 7 on Erigeron brevis 14-21 days after application. Detailed Implementation

[0059] It should be noted that, in this application, the chemical name of the compound "isoxafenacil" is: 3-(2-chloro-4-fluoro-5-(3-methyl-2,6-dioxo-4-trifluoromethyl-3,6-dihydropyrimidin-1(2H)-yl)-phenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylic acid ethyl ester.

[0060] The source information of the raw materials used in the following examples is shown in Table 1.

[0061] Table 1

[0062] First set of embodiments

[0063] The first set of embodiments provides a water-in-oil emulsion containing pyrimethanil, including Examples 1-5. By mass percentage, the raw materials for its preparation include pyrimethanil, solvent, emulsifier, antifreeze, defoamer, stabilizer, and water. The difference between the raw materials in Examples 1-5 is the amount of stabilizer added and the amount of water added. The specific amounts are shown in Table 1-1.

[0064] Table 1-1

[0065] The stabilizer is disodium hydrogen phosphate.

[0066] The solvent is a combination of 10 wt% co-solvent and 30 wt% main solvent.

[0067] The co-solvent is decanoic acid.

[0068] The main solvent is 150# solvent oil.

[0069] The emulsifier is a combination of castor oil polyoxyethylene ether of type 3600B and EOPO block polyether of type 1125; the mass ratio of castor oil polyoxyethylene ether of type 3600B to EOPO block polyether of type 1125 is 2.5:1.5.

[0070] The antifreeze is propylene glycol.

[0071] The defoamer is Momentive SAG1572.

[0072] The water is deionized water.

[0073] The first set of embodiments provides a method for preparing a water-in-oil emulsion containing pyrimethanil, comprising the following steps:

[0074] S1. Add the solvent to the oil phase preparation vessel, then add pyrimethanil to the oil phase preparation vessel and heat the mixture of solvent and pyrimethanil to 50°C to dissolve and clarify. Then add emulsifier to the mixture and stir evenly to obtain the oil phase.

[0075] S2. Aqueous phase is obtained by mixing water, antifreeze, and defoamer;

[0076] S3. Add the oil phase to the aqueous phase and shear to obtain a mixture, then add a stabilizer to the mixture and mix thoroughly to obtain a pyrimethanil-containing emulsion.

[0077] The mixture obtained after shearing in step S3 can be a homogeneous liquid.

[0078] The particle size D of the pyrimethanil-containing water emulsion obtained in Examples 1, 2, 3, 4, and 5 is described. 97 It is 2-3 μm.

[0079] Second set of embodiments

[0080] The second set of embodiments provides a water-in-oil emulsion containing pyrimethanil, including Examples 6-10. By mass percentage, the raw materials for its preparation include pyrimethanil, solvent, emulsifier, antifreeze, defoamer, stabilizer, and water. The difference in the raw materials for the preparation in Examples 6-10 is the different amounts of stabilizer and water added. The specific amounts are shown in Table 2-1.

[0081] Table 2-1

[0082] The stabilizer is triethanolamine.

[0083] The solvent comprises 10 wt% co-solvent and 30 wt% main solvent.

[0084] The co-solvent is decanoic acid.

[0085] The main solvent is 150# solvent oil.

[0086] The emulsifier is a combination of castor oil polyoxyethylene ether (EMULPON CO-360) and EOPO block polyether (ETHYLAN NS-500LQ); the mass ratio of castor oil polyoxyethylene ether (EMULPON CO-360) to EOPO block polyether (ETHYLAN NS-500LQ) is 2.5:1.5.

[0087] The antifreeze is propylene glycol.

[0088] The defoamer is Momentive SAG1572.

[0089] The water is deionized water.

[0090] The second set of embodiments provides a method for preparing a water-in-oil emulsion containing pyrimethanil, comprising the following steps:

[0091] S1. Add the solvent to the oil phase preparation vessel, then add pyrimethanil to the oil phase preparation vessel and heat the mixture of solvent and pyrimethanil to 50°C to dissolve and clarify. Then add emulsifier to the mixture and stir evenly to obtain the oil phase.

[0092] S2. Aqueous phase is obtained by mixing water, antifreeze, and defoamer;

[0093] S3. Add the oil phase to the aqueous phase and shear to obtain a mixture, then add a stabilizer to the mixture and mix thoroughly to obtain a pyrimethanil-containing emulsion.

[0094] The mixture obtained after shearing in step S3 can be a homogeneous liquid.

[0095] The particle size D of the pyrimethanil-containing water emulsion obtained in Examples 6, 7, 8, 9, and 10 is... 97 It is 2-3 μm.

[0096] Third set of embodiments

[0097] The third set of embodiments provides a water-in-oil emulsion containing pyrimethanil, including Examples 11-12. By mass percentage, the raw materials for its preparation include pyrimethanil, solvent, emulsifier, antifreeze, defoamer, stabilizer, and water. The difference lies in the type of stabilizer, and the specific amount added is shown in Table 3-1.

[0098] Table 3-1

[0099] The solvent comprises 10 wt% co-solvent and 30 wt% main solvent.

[0100] The co-solvent is decanoic acid.

[0101] The main solvent is 150# solvent oil.

[0102] The emulsifier is a combination of castor oil polyoxyethylene ether of type EMULPON CO-360 and EOPO block polyether of type 5000HM; the mass ratio of castor oil polyoxyethylene ether of type EMULPON CO-360 to EOPO block polyether of type 5000HM is 2.5:1.5.

[0103] The antifreeze is propylene glycol.

[0104] The defoamer is Momentive SAG1572.

[0105] The water is deionized water.

[0106] The third set of embodiments provides a method for preparing a water-in-oil emulsion containing pyrimethanil, comprising the following steps:

[0107] S1. Add the solvent to the oil phase preparation vessel, then add pyrimethanil to the oil phase preparation vessel and heat the mixture of solvent and pyrimethanil to 50°C to dissolve and clarify. Then add emulsifier to the mixture and stir evenly to obtain the oil phase.

[0108] S2. Aqueous phase is obtained by mixing water, antifreeze, and defoamer;

[0109] S3. Add the oil phase to the aqueous phase and shear to obtain a mixture, then add a stabilizer to the mixture and mix thoroughly to obtain a pyrimethanil-containing emulsion.

[0110] The mixture obtained after shearing in step S3 can be a homogeneous liquid.

[0111] The particle size D of the pyrimethanil-containing water emulsion obtained in Examples 11 and 12 is... 97 It is 2-3 μm.

[0112] Fourth set of embodiments

[0113] The fourth set of examples provides a water-in-oil emulsion containing pyrimethanil, including Examples 13-16. By mass percentage, the raw materials for its preparation include pyrimethanil, decanoamide, 150# solvent oil, castor oil polyoxyethylene ether of type 3600B, EOPO block polyether of type 1125, antifreeze propylene glycol, defoamer Momentive SAG1572, stabilizer disodium hydrogen phosphate, and deionized water. The specific amounts added are shown in Table 4-1.

[0114] Table 4-1

[0115] The fourth set of embodiments provides a method for preparing a water-in-oil emulsion containing pyrimethanil, and the specific implementation method is the same as that in the first set of embodiments.

[0116] The particle size D of the pyrimethanil-containing water emulsion obtained in Examples 13, 14, 15, and 16 is... 97 It is 2-3 μm.

[0117] Fifth set of embodiments

[0118] The fifth set of examples provides a water-in-oil emulsion containing pyrimethanil, including Examples 17-20. By mass percentage, the raw materials for its preparation include pyrimethanil, decanoamide, 150# solvent oil, castor oil polyoxyethylene ether of model EMULPON CO-360, EOPO block polyether of model ETHYLAN NS-500LQ, antifreeze propylene glycol, defoamer Momentive SAG1572, stabilizer triethanolamine, and deionized water. The specific amounts added are shown in Table 5-1.

[0119] Table 5-1

[0120] The fifth set of embodiments provides a method for preparing a water-in-oil emulsion containing pyrimethanil, and the specific implementation method is the same as that in the second set of embodiments.

[0121] The particle size D of the pyrimethanil-containing water emulsion obtained in Examples 17, 18, 19, and 20 is... 97 It is 2-3 μm.

[0122] Performance testing

[0123] The following performance tests will use both hot and cold storage methods to store the pyrimethanil-containing water-in-oil emulsions provided in Examples 1-20. Hot storage conditions: 54℃±2℃ for 14 days; cold storage conditions: 0℃±2℃ for 7 days.

[0124] The pyrimethanil-containing emulsions provided in this disclosure need to have a 2-year shelf-life stability. The time-temperature equivalence test scheme is adopted, and storage at 54°C for 14 days is equivalent to a 2-year shelf-life storage condition.

[0125] When the decomposition rate of pyrimethanil in the water-based emulsion containing pyrimethanil is less than 5% after heat storage, it is considered a qualified product and can maintain its stability for 2 years of shelf life.

[0126] 1. Storage stability test:

[0127] Observe whether the water-in-oil emulsion containing pyrimethanil provided in Examples 1-20 above exhibits water separation, stratification, demulsification, or phase inversion after hot and cold storage. If water separation, stratification, demulsification, or phase inversion occurs, it is considered abnormal; if no such problems occur, it is considered normal. The test results for Examples 1-5 are shown in Table 1-2; the test results for Examples 6-10 are shown in Table 2-2; the test results for Examples 11 and 12 are shown in Table 3-2; the test results for Examples 13-16 are shown in Table 4-2; and the test results for Examples 17-20 are shown in Table 5-2.

[0128] Figure 1 shows the normal state of the water-in-oil emulsion containing pyrimethanil.

[0129] Figure 2 shows the water separation and stratification state of the water emulsion containing pyrimethanil.

[0130] Figure 3 shows the demulsification and phase inversion state of the water-in-oil emulsion containing pyrimethanil.

[0131] 2. pH test:

[0132] The pH of the pyrimethanil-containing emulsions provided in Examples 1-12 was tested at room temperature (25°C) before storage. The test results for Examples 1-5 are shown in Table 1-2; the test results for Examples 6-10 are shown in Table 2-2; and the test results for Examples 11 and 12 are shown in Table 3-2.

[0133] 3. Decomposition rate test of pyrimethanil:

[0134] The decomposition rate of pyrimethanil-containing emulsions provided in Examples 1-12 was tested after 14 days of heat storage; the test results of Examples 1-5 are shown in Table 1-2; the test results of Examples 6-10 are shown in Table 2-2; and the test results of Examples 11 and 12 are shown in Table 3-2.

[0135] Decomposition rate of pyrimethanil (%) = (1 - content of pyrimethanil after heat storage / content of pyrimethanil under normal temperature storage) * 100%.

[0136] 4. Application testing:

[0137] The pyrimethanil-containing emulsions provided in Examples 2, 6, 7, 8, 9, 10, 11, and 12 were diluted with water of different temperatures and hardnesses to observe their dilution stability. When the observation results showed no flocculation, no stratification, and no precipitation, they were deemed qualified; when flocculation, stratification, and precipitation occurred, they were deemed unqualified. The test results are shown in 5-3.

[0138] 5. Weed control effect test:

[0139] The pyrimethanil-containing emulsifiable concentrate provided in Example 7 was used to apply pesticides to reeds, goosegrass, and fleabane, and the effects of the pesticide application were observed.

[0140] (1) Target of application: Reeds.

[0141] Location of application: Nanpi County, Cangzhou City.

[0142] Application rate: 60 mL / mu.

[0143] The weed control effect on reeds before, 3 days after, and 7 days after application of the herbicide is shown in Figure 4.

[0144] (2) Target of application: Goosegrass.

[0145] Application location: Gaoqiao Town, Changsha County, Changsha City, Hunan Province.

[0146] Application rate: 60 mL / mu.

[0147] The weed control effect on *Eleusine indica* before, 3 days after, 7 days after, 14 days after, and 21 days after application of the herbicide is shown in Figures 5 and 6.

[0148] (3) Target of application: Erigeron brevis.

[0149] Application location: Huanghua Town, Changsha County, Changsha City, Hunan Province.

[0150] Application rate: 60 mL / mu.

[0151] The weed control effect of Erigeron fleabane was tested before, 3 days after, 7 days after, 14 days after, and 21 days after application of the herbicide. The results are shown in Figures 7 and 8.

[0152] As shown in Figure 4, the pyrimethanil-containing emulsifiable concentrate provided in this application has the characteristic of rapid weed control on reeds.

[0153] As can be seen from Figures 5 and 6, the pyrimethanil-containing emulsifiable concentrate provided in this application has the characteristic of rapid weed control of goosegrass.

[0154] As can be seen from Figures 7 and 8, the pyrimethanil-containing emulsifiable concentrate provided in this application has the characteristic of rapid weed control of Erigeron brevis.

[0155] Table 1-2

[0156] As shown in Table 1-2, the pyrimethanil-containing emulsions obtained by using disodium hydrogen phosphate as a stabilizer in combination with pyrimethanil exhibited the following characteristics: when the disodium hydrogen phosphate addition was 0%, the decomposition rate of pyrimethanil after heat storage was greater than 5%, classifying it as a substandard product. When the disodium hydrogen phosphate addition was 0.1%, it provided stability, with a heat storage decomposition rate of <5% and stable appearance without any abnormalities. Furthermore, with increasing disodium hydrogen phosphate dosage, the decomposition rate of pyrimethanil after heat storage did not show a positive correlation decreasing trend. When the disodium hydrogen phosphate addition was greater than or equal to 0.3%, all pyrimethanil-containing emulsions experienced unstable phenomena such as water separation, stratification, demulsification, and phase inversion after heat storage. Moreover, the addition of disodium hydrogen phosphate... The dosage affects the pH of the pyrimethanil-containing emulsion. Controlling the pH of the pyrimethanil-containing emulsion to 7.20-7.80 will prevent water separation, stratification, demulsification, and phase inversion during cold storage, thus reducing the decomposition rate of pyrimethanil during storage and at high temperatures. Furthermore, when the pH of the pyrimethanil-containing emulsion is 7.51-7.70, it will not exhibit unstable issues such as water separation, stratification, demulsification, and phase inversion after storage at high temperatures, resulting in a qualified product. When the addition amount of disodium hydrogen phosphate is 1 wt%, demulsification and phase inversion after shearing will occur during the preparation of the pyrimethanil-containing emulsion.

[0157] Table 2-2

[0158] As shown in Table 2-2, using triethanolamine as a stabilizer in combination with EOPO block polyether and castor oil polyoxyethylene ether, and controlling the pH of the pyrimethanil-containing water emulsion to 8.0-10.0, will prevent problems such as water separation, demulsification, and phase inversion during storage. Furthermore, it can reduce the pyrimethanil decomposition rate of the water emulsion to less than 5% during storage and under high-temperature storage conditions, thus obtaining a qualified product. Additionally, it prevents demulsification and phase inversion after storage at high temperatures, ensuring a qualified product.

[0159] Table 3-2

[0160] As shown in Table 3-2, when pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris(2,4-di-tert-butylphenyl) phosphite is used as a stabilizer, and combined with EOPO block polyether and castor oil polyoxyethylene ether respectively, the pH of the pyrimethanil-containing water emulsion is controlled at 5.0-6.0, preventing post-shear phase inversion. This reduces the pyrimethanil decomposition rate to less than 5% under both cold and hot storage, resulting in qualified products. Furthermore, it prevents demulsification and phase inversion after high-temperature storage, ensuring qualified products. During 14 days of hot storage, the pH change is small, and there is no pyrimethanil decomposition, thus improving the stability of the pyrimethanil-containing water emulsion.

[0161] Table 4-2

[0162] Table 5-2

[0163] The test results in Tables 4-2 and 5-2 show that when EOPO block polyether and castor oil polyoxyethylene ether are combined with a stabilizer at a mass ratio of (1-3):(1-3), the resulting pyrimethanil-containing emulsion does not exhibit water separation, stratification, demulsification, or phase inversion during cold and hot storage. This improves the storage stability of the pyrimethanil-containing emulsion and ensures a 2-year shelf-life stability.

[0164] Table 5-3

[0165] As can be seen from Table 5-3, the pyrimethanil-containing emulsifiable concentrates provided in Examples 2, 6, 7, 8, 9, 10, 11, and 12 of this application showed no flocculation, stratification, or precipitation when diluted with water of different hardness and temperature, and all were in a qualified state. This shows that the pyrimethanil-containing emulsifiable concentrates provided in the above examples are highly versatile and can be applied to water in different regions for dilution and application.

Claims

1. An emulsion in water containing isoxafenacil, wherein in percentage by mass, raw materials for preparing the emulsion in water comprise 5%-30% of isoxafenacil, 10%-40% of a solvent, 3%-5% of an emulsifier, 3%-5% of an anti-freezing agent, 0.01%-0.1% of a defoaming agent, 0.1%-1% of a stabilizer, and a remainder of water.

2. The emulsion in water containing isoxafenacil according to claim 1, wherein in percentage by mass, the raw materials for preparing the emulsion in water comprise 10%-20% of the isoxafenacil.

3. The emulsion in water containing isoxafenacil according to claim 1, wherein the emulsifier comprises one or two of ethylene oxide-propylene oxide (EOPO) block polyether and castor oil polyoxyethylene ether.

4. The emulsion in water containing isoxafenacil according to claim 3, wherein a mass ratio of the castor oil polyoxyethylene ether to the EOPO block polyether is (1-3):(1-3).

5. The emulsion in water containing isoxafenacil according to any one of claims 1 to 4, wherein the stabilizer comprises one or more of disodium hydrogen phosphate, triethanolamine,              pentaerythritol              tetrakis[P-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tris(2,4-di-tert-butylphenyl)phosphite.

6. The emulsion in water containing isoxafenacil according to claim 5, wherein the stabilizer is the disodium hydrogen phosphate, and the emulsion in water containing isoxafenacil has a pH of 7.20-7.80.

7. The emulsion in water containing isoxafenacil according to claim 5, wherein the stabilizer is the triethanolamine, and the emulsion in water containing isoxafenacil has a pH of 8.0-10.0.

8. The emulsion in water containing isoxafenacil according to claim 5, wherein the stabilizer is one or two of the pentaerythritol tetrakis[P-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and the tris(2,4-di-tert-butylphenyl)phosphite, and the emulsion in water containing isoxafenacil has a pH of 5.0-6.0.

9. A method for preparing the emulsion in water containing isoxafenacil according to any one of claims 1 to 8, comprising the following steps:S1. putting the solvent into an oil phase preparation kettle, and then sequentially putting the isoxafenacil and the emulsifier into the oil phase preparation kettle for stirring to obtain an oil phase;S2. mixing the water, the anti-freezing agent, and the defoaming agent to obtain an aqueous phase; andS3. adding the oil phase into the aqueous phase for shearing to obtain a mixture, and adding the stabilizer into the mixture for mixing to obtain the emulsion in water containing isoxafenacil.

10. The method for preparing the emulsion in water containing isoxafenacil according to claim 9, wherein the emulsion in water containing isoxafenacil obtained in the step S3 has a particle size D97 of 2-3gm.

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